Last week I was telling a friend about my 13-year old son's weight training progress. She cautioned that her daughter's gymnastics coach advised that kids should not weight train until 16 years old to avoid growth plate injuries. Seriously, the coach who has my friend's perpetually injured, 9 year old daughter flinging, contorting, lifting and slamming her body around for 15+ hours a week in competitive gymnastics believes that moving a bar through a natural range of motion in a controlled manner 3 days per week is far too risky an activity.